This invention relates to the art of electrically-operated gas sensors, and more particularly to a new and improved signal conditioner for such sensors.
Electronic chemical gas sensors are used both for long-term or chronic monitoring of environmental gases, especially in buildings, and to provide warnings of acute gas build-up due to a chemical incident or attack. These sensors may involve a wide range of technologies and the supporting electronics, or signal conditioner, must match the technology. Commercial gas monitors typically have a small, fixed number of sensors for specific gases (e.g. oxygen or chlorine) and these are often factory-installed and difficult to change.
In emergency situations, the type of gas sensor required may not be known until the incidence occurs. For these situations, it would be desirable to have gas sensors available which are “plug-and-play” or automatically configurable. The multi-element smart gas sensor invention described herein is intended to allow commercial, off-the-shelf gas sensors to be implemented in portable gas monitors and provide this automatic configuration.
Another reason for flexibility in a monitor's capacity to use different sensor technologies is that sensors are not interchangeable as are most electronic components. Some sensors are made only in one factory (world-wide) and are in short supply. Also very often the individual responses and calibrations differ.
A standard format for digital smart sensors (IEEE 1451.4 or Dot 4) has been developed by a national/international committee sponsored by NIST. A major purpose is to facilitate plug-and-play of sensors. One aspect is the Transducer Electronic Data Sheet (TEDS) which allows sensor configurations and calibration information to be stored (in digital form) with a sensor, along with its ID. The TEDS feature of this open standard is used in this invention.